I took it with the C-4040/PT-10, YS90DX strobe. The EXIF...
ISO100
f6.3
1/100
Spot Macro
Strobe setting was #5
If I remember correctly, the depth was 55-60ft. I was close, probably about 12-14 inches. I was zoomed all the way out so I could get his whole face in the picture. I couldn't back-up because of people behind me trying to see and he couldn't back up because of the wall and several more big 'Cuda's behind him. It was a tense few minutes! He's actually one of the regular characters on Newman's Wall there at CCV and is used to divers and their cameras. Still, I'm never comfortable in tight quarters with things with teeth...you never known when they'll feel threathened and decide to come through you to get out!
You've mentioned several times about your 5050 being slow to focus. Are you using the half-press method? If you use that it's not so bad. And to help avoid fish butts on those fish that won't sit still and pose, keep following them with your camera as you press the button. Sort of like leading skeet when you shoot. It takes a split second for the camera to capture the picture and if you're leading the fish, you'll stay in focus and get the shot.